This invention relates generally to systems utilizing film to package articles contained in trays and, more particularly, to a system wherein a wrapping machine, a weighing scale and a labeler interact and cooperate with one another to produce a compact, high efficiency packaging system.
A variety of film wrapping machines are known in the prior art. In modern wrapping machines, multiple film widths and lengths may be used to wrap trayed commodities. For example, one commercially available machine includes a sensing system which determines the length and the width of a trayed commodity to be wrapped. Based on the sensed length and width characteristics, the wrapping machine selects one of two differing width film rolls and the length of the film sheet drawn from the selected roll. While this wrapping machine is an improvement over earlier machines which utilize a fixed length of a single width film to wrap all packages regardless of size, the use of the length and the width of a tray alone to select the film sheet size does not permit an optimal sized sheet of material to be drawn.
Computing weighing scales and labelers which print and apply price labels to packages as well as combinations of the two are also known in the art. A computer or other electronic means is included within the scale or labeler for calculating the price for the packaged commodity. The price is calculated by effectively multiplying the net weight of the packaged commodity times the commodity price per unit weight which is stored into a memory of the computer. Commodity net weight is determined by compensating for the tare weight or weight of the packaging material.
In the prior art, tare weight compensation has been performed by zeroing the scale while an exemplar of the packaging material is on the scale weighing platform. The exemplar can be a tray alone, if the trayed commodity is weighed before wrapping, or a tray and sheet of film if weighed after wrapping.
Alternately, in some packaging systems, the expected tare weight is stored together with the identification of the commodity and the price per unit weight of the commodity. The expected tare weight is based on the packaging material which is ordinarily used to package the particular commodity such as a tray size and diaper. Thus, the package is weighed to obtain a gross weight and the stored tare weight for the given commodity is subtracted from the gross weight by the computer. The net weight thus determined, coupled with the price per unit weight, determines the price to be charged for the package.
The typical operation of a prior art packaging system is to initially place a commodity to be packaged onto a supporting tray. The trayed commodity is then fed into a wrapping machine where a sheet of film is wrapped about it and secured beneath the tray to complete a package. The package is then conveyed either mechanically or manually to a combination computing weighing scale and labeler. At the scale/labeler station, the price of the package is computed, a price label is printed and the label is applied to the package.
In order to conserve space, a commercially available packaging system has been developed which combines a weighing scale, a wrapping machine and a label printer into a single unit. Even though these machines are combined into a single, relatively compact unit, there is no cooperative interaction between the individual machines. That is to say, each of the machines performs its standard function: the scale weighs the package, the wrapping machine wraps the package and the label printer prints a label in response to weight signals generated by the scale. Furthermore, since label generation/application is downstream from the wrapping operation, label information must be stored and delayed so that labels correctly correspond with wrapped packages. Such information storage and delay lead to problems in restarting the system when the system is stopped due to operating problems.
It is, thus, apparent that while wrapping machines, computing weighing scales and label printers/appliers are available and have been packaged in various combinations, the functions and characteristics of the individual units have not been interrelated one to another to arrive at a cooperative, integrated packaging system.